MECHANICAL CONNECTIONS BETWEEN ELASTIN AND COLLAGEN

The ligament supporting the leading edge of birds' wings is a connecti ve tissue structure with unusual morphologic and elastic features. Its center section is made of a highly extensible composite of elastin an d collagen fibers and its two end sections of nearly inextensible pure collagen; these are joined end-to-end in short interdigitating juncti ons. Substantial forces are transmitted through the junctions showing that collagen and elastin are mechanically connected. The junctions an d elastic segment are sufficiently strong that when the intact ligamen t is maximally strained, the point of failure is commonly in the colla genous segments or their attachments to the tissues of origin or inser tion. Here we outline the morphology and describe static force-length properties of this ligament.